Improved evaluator errors

src/entry/unix/unix.rs

@@ -11,6 +11,7 @@ use termion::{
 	style,
 };
 
+use crate::tokens::EvalError;
 use super::promptbuffer::PromptBuffer;
 use crate::parser;
 
@@ -103,9 +104,19 @@ pub fn main() -> Result<(), std::io::Error> {
 										)?;
 									},
 
-									Err(_) => {
+									Err(EvalError::BadMath) => {
 										write!(
-											stdout, "\n  {}{}Mathematical Error: {}Failed to evaluate expression.{}\r\n\n",
+											stdout, "\n  {}{}Mathematical Error: {}Failed to evaluate expression{}\r\n\n",
+											style::Bold,
+											color::Fg(color::Red),
+											style::Reset,
+											color::Fg(color::Reset),
+										)?;
+									},
+
+									Err(EvalError::IncompatibleUnit) => {
+										write!(
+											stdout, "\n  {}{}Evaluation Error: {}Incompatible units{}\r\n\n",
 											style::Bold,
 											color::Fg(color::Red),
 											style::Reset,

src/tokens/function.rs

@@ -1,6 +1,7 @@
 use std::collections::VecDeque;
 
 use crate::tokens::Token;
+use crate::tokens::EvalError;
 use crate::tokens::Operator;
 
 #[derive(Debug)]
@@ -65,13 +66,13 @@ impl Function {
 		}
 	}
 
-	pub fn apply(&self, args: &VecDeque<Token>) -> Result<Token, ()> {
+	pub fn apply(&self, args: &VecDeque<Token>) -> Result<Token, EvalError> {
 		if args.len() != 1 {panic!()};
 		let a = args[0].as_number();
 		let Token::Number(q) = a else {panic!()};
 
 		if !q.unitless() {
-			return Err(());
+			return Err(EvalError::IncompatibleUnit);
 		}
 
 		match self {

src/tokens/mod.rs

@@ -4,4 +4,9 @@ mod token;
 
 pub use crate::tokens::token::Token;
 pub use crate::tokens::function::Function;
-pub use crate::tokens::operator::Operator;
+pub use crate::tokens::operator::Operator;
+
+pub enum EvalError {
+	BadMath,
+	IncompatibleUnit
+}

src/tokens/operator.rs

@@ -3,8 +3,10 @@ use std::cmp::Ordering;
 
 use crate::tokens::Token;
 use crate::tokens::Function;
+use crate::tokens::EvalError;
 use crate::quantity::Quantity;
 
+
 /// Operator types, in order of increasing priority.
 #[derive(Debug)]
 #[derive(Clone)]
@@ -331,7 +333,7 @@ impl Operator {
 }
 
 impl Operator{
-	pub fn apply(&self, args: &VecDeque<Token>) -> Result<Token, ()> {
+	pub fn apply(&self, args: &VecDeque<Token>) -> Result<Token, EvalError> {
 		match self {
 			Operator::ImplicitMultiply |
 			Operator::Sqrt |
@@ -352,7 +354,7 @@ impl Operator{
 				let args = args[0].as_number();
 
 				if let Token::Number(v) = args {
-					if v.is_zero() { return Err(()); }
+					if v.is_zero() { return Err(EvalError::BadMath); }
 					return Ok(Token::Number(
 						Quantity::new_rational(1f64).unwrap()/v
 					));
@@ -371,7 +373,7 @@ impl Operator{
 					if let Token::Number(v) = j {
 
 						if sum.unit() != v.unit() {
-							return Err(());
+							return Err(EvalError::IncompatibleUnit);
 						}
 
 						sum += v;
@@ -406,12 +408,12 @@ impl Operator{
 					if let Token::Number(vb) = b {
 
 						if !(va.unitless() && vb.unitless()) {
-							return Err(());
+							return Err(EvalError::IncompatibleUnit);
 						}
 
-						if vb <= Quantity::new_rational(1f64).unwrap() { return Err(()); }
-						if va.fract() != Quantity::new_rational(0f64).unwrap() { return Err(()); }
-						if vb.fract() != Quantity::new_rational(0f64).unwrap() { return Err(()); }
+						if vb <= Quantity::new_rational(1f64).unwrap() { return Err(EvalError::BadMath); }
+						if va.fract() != Quantity::new_rational(0f64).unwrap() { return Err(EvalError::BadMath); }
+						if vb.fract() != Quantity::new_rational(0f64).unwrap() { return Err(EvalError::BadMath); }
 
 						return Ok(Token::Number(va%vb));
 					} else { panic!(); }
@@ -427,11 +429,11 @@ impl Operator{
 					if let Token::Number(vb) = b {
 
 						if va.unit() != vb.unit() {
-							return Err(());
+							return Err(EvalError::IncompatibleUnit);
 						}
 
 						let p = va.pow(vb);
-						if p.is_nan() {return Err(());}
+						if p.is_nan() {return Err(EvalError::BadMath);}
 						return Ok(Token::Number(p));
 					} else { panic!(); }
 				} else { panic!(); }
@@ -444,11 +446,11 @@ impl Operator{
 				if let Token::Number(v) = args {
 
 					if !v.unitless() {
-						return Err(());
+						return Err(EvalError::IncompatibleUnit);
 					}
 
-					if !v.fract().is_zero() { return Err(()); }
-					if v > Quantity::new_rational(50_000f64).unwrap() { return Err(()); }
+					if !v.fract().is_zero() { return Err(EvalError::BadMath); }
+					if v > Quantity::new_rational(50_000f64).unwrap() { return Err(EvalError::IncompatibleUnit); }
 
 					let mut prod = Quantity::new_rational(1f64).unwrap();
 					let mut u = v.clone();

src/tokens/token.rs

@@ -1,8 +1,10 @@
 use std::collections::VecDeque;
 
+use crate::tokens::EvalError;
 use crate::tokens::Operator;
 use crate::quantity::Quantity;
 
+
 /// Tokens represent logical objects in an expession.
 ///
 /// Tokens starting with `Pre*` are intermediate tokens, and
@@ -60,7 +62,7 @@ impl Token {
 	}
 
 	#[inline(always)]
-	pub fn eval(&self) -> Result<Token, ()> {
+	pub fn eval(&self) -> Result<Token, EvalError> {
 		Ok(match self {
 			Token::Number(_) => { self.clone() },
 			Token::Constant(v,_) => { Token::Number(v.clone()) },
@@ -96,7 +98,7 @@ impl Token {
 	}
 
 
-	pub fn evaluate(&self) -> Result<Token, ()> {
+	pub fn evaluate(&self) -> Result<Token, EvalError> {
 		let mut g = self.clone();
 		let mut coords: Vec<usize> = Vec::with_capacity(16);
 		coords.push(0);